The present invention is directed to non-fat cream cheese products and methods for manufacturing such non-fat cream cheese products. The non-fat cream cheese products of the present invention have creamy non-syneresing texture and aromatic flavor similar to that of fat-containing cream cheese.
Cream cheese is a soft, mild acid-coagulated uncured cheese made from a mixture of cream and milk. Cream cheese is a dry, soft, pliable curd, which is used for cheesecake, salads, dips, and spreads. The flavor of conventional cream cheese is described as slight acid and nutty often with a hint of diacetyl. Cream cheese is stored under refrigeration conditions and the body of cream cheese is smooth and butter-like. The texture and body of cream cheese at refrigeration temperatures is such that the cream cheese can be sliced and spread. In making conventional cream cheese, sweet whole milk and/or skim milk and sweet cream are blended in pre-selected proportions to form a cream cheese mix. The cream cheese mix normally has a butterfat content of from about 10 percent to about 14 percent. After culturing, the finished cream cheese has a butterfat content of from about 33 percent to about 35 percent. Reduced fat or xe2x80x9clightxe2x80x9d cream cheese products can be produced from proportionately lower-fat cream cheese mixes; although such xe2x80x9clightxe2x80x9d cream cheese products generally have excellent flavor and texture, they still retain a relatively high butterfat content.
In manufacture, a conventional cream cheese mix is first pasteurized and homogenized. After cooling (usually to a temperature between 62xc2x0 F. and 92xc2x0 F.), it is inoculated with a conventional lactic acid culture. Rennet may be used to aid the coagulation of the mixture. It is held at the inoculation temperature until it has ripened and a coagulum is formed. The total acidity of the coagulum is typically from about 0.6 percent to about 0.9 percent (calculated as percent equivalent lactic acid); the pH is generally about 4.1 to about 4.9.
After the desired acidity is obtained, the curd is separated from the whey and is thereafter packaged. One well known process for making cream cheese and separating cream cheese curd from whey includes a mechanical separation of the curd from the whey such as disclosed in U.S. Pat. No. 2,387,276 to Link. In accordance with the method of the Link patent, after the mix is ripened to form a coagulum, the coagulum is heated to an elevated temperature to break the viscosity of the mix. The heated mix is centrifuged at the elevated temperature to separate the curd from the whey. Such conventional cream cheese has a characteristic, smooth, creamy consistency and delicate taste and aroma.
There has been considerable effort directed to providing cream cheese type products which have the texture, smoothness and organoleptic properties of cream cheese, but which are fat-free or have very significantly reduced levels of fat. Low fat, low calorie foods which look and taste similar to their full fat, higher calorie counterparts are desirable alternative products for consumers. Researchers in the food industry have concentrated on developing food products which are nutritious and palatable, containing substantially reduced levels of high calorie, fat-containing ingredients. This is particularly true in the dairy industry where low calorie, low-fat products such as skim milk, yogurt and reduced fat ice cream have been successfully marketed.
The high fat levels in some dairy products, such as cream cheese (with a fat content of at least about 33 percent) or xe2x80x9clightxe2x80x9d cream cheese (with a fat content of at least about 16.5 percent) have been thought to be important in maintaining a desirable creamy mouthfeel and characteristic flavor, and to avoid the grainy texture associated with some low fat cream cheese products. Nevertheless, significant effort has been devoted to developing imitation cream cheese products which contain reduced fat levels. Examples of such efforts are disclosed in U.S. Pat. No. 2,161,159 to Lundstedt et al. and U.S. Pat. No. 3,929,892 to Hynes et al. However, the fat content of the cream cheese products produced by such methods still exceeds about 10 percent fat. It would be desirable to reduce the fat content well below 10 percent.
Efforts have been made to develop very low butterfat content imitation cream cheese products having low calorie content. U.S. Pat. Nos. 4,244,983 and 4,379,175 to Baker describe imitation cream cheese products having butterfat content of less than about 2 percent, and which have about 60 calories per serving. However, U.S. Pat. No. 4,724,152 describes use of soft, unripened cultured cheese curd, such as cottage or bakers cheese curd, in a low fat product. According to this patent, the resulting products do not closely duplicate the desired creamy and full-bodied consistency of full fat cream cheese. More recently, U.S. Pat. No. 5,079,024, to Crane, and U.S. Pat. No. 5,180,604, to Crane et al., describe manufacture of fat-free cream cheese from concentrated skim milk, dry cottage cheese curd, gums and bulking agents, which are homogenized to provide a fat-free cream cheese product. However, while these processes provide desirable products, they typically involve multiple mixing steps and the use of relatively expensive cottage cheese curd, which adds to the cost of the fat-free cream cheese product.
There are many functions of lactic acid bacteria in cheese, including acid production, development of curd strength, enhancement of cheese yield, dissociation of colloidal calcium phosphate, proteolysis in cheese, production of antimicrobials, control of certain non-starter organisms and pathogens, and flavor development. (See, e.g., Nauth, K. R., Cheese, Dairy Science Technology Handbook, Vol. 2, Y. H. Hui (Ed) VCH Publishers, New York, p. 174, 1993.) These functions are more or less common to all lactic acid bacteria starter cultures which include mesophilic (Streptococcus lactis, S. cremoris and S. diacetylactis) and thermophilic (Streptococcus thermophilus, L. bulgaricus, L. helveticus and L. lactis) culture organisms. However, within the diversity of these organisms there exist strain(s) which have additional characteristics such as fermentation of citrate with the production of diacetyl and CO2.
Another property of certain strains of lactic starter bacteria is the production of slime-forming exocellular polysaccharides (EPS), also termed xe2x80x9cropinessxe2x80x9d, which is typically undesirable in most dairy fermentations. Ropy characteristics in lactic starter cultures are known to adversely affect routine processing operations in dairy fermentations, thereby resulting in economic losses to the industry. For example, during cheese manufacture, a ropy condition in a starter may adversely affect acid production and curd formation, resulting in texture defects.
Bacterial cells may synthesize exocellular polysaccharides in two basic forms, either as a capsule intimately associated with the cell surface, or secreted into the environment. In some cases, both capsular and unattached polysaccharides are produced by the same microbe. Distinguishing between the two forms can be difficult. (Cerning, J., Exopolysaccharides Produced by Lactic Acid Bacteria, FEMS Microbiol. Rev., 87:113-130, 1990.) Depending on their structural relationship to the bacterial cell, they have been variously referred to as slime, capsular or microcapsular polysaccharides. The term exopolysaccharides (EPS) (as proposed by Sutherland, I. W., Bacterial Exopolysaccharides, Adv. Microbial Physiol., 8:143-212, 1972) provides a general term for all these forms of bacterial polysaccharides found outside the cell wall.
There are a number of sugars detected in EPS produced by S. thermophilus and L. bulgaricus. For example, Cerning (1990) showed that EPS of ropy L. bulgaricus contains galactose, glucose and rhamnose in approximate molar ratio of 4:1:1; whereas ropy S. thermophilus contains only galactose and glucose. When cultures of S. thermophilus were propagated in milk, the EPS was found to contain galactose, glucose and n-acetyl-galactosamine in a ratio of 2:1:1.
The terminology xe2x80x9cexocellular-polysaccharidexe2x80x9d is used interchangeably with xe2x80x9cropiness/mucoidnessxe2x80x9d in relation to lactic acid bacteria. (Vedamuthu, et al., Involvement of a Plasmid in Production of Ropiness (See, e.g., Mucoidness in Milk Cultures by Streptococcus cremoris, MS. Appl. Environ. Microbiol., 51:677-682, 1986; Schellhaas, et al., Rheological and Scanning Electron Microscopic Examination of Skim Milk Gels Obtained by Fermenting with Ropy and Non-Ropy Strains of Lactic Acid Bacteria, Food Microstructure, 4:279-287 (1985); Ranganathan, et al., Studies on Factors Affecting Ropiness in Streptococcus Lactis, Milchwissenschaft, 34:333-335, 1979; Voscovo, et al., Plasma-Encoded Ropiness Production in Lactobacillus casei ssp. casei, Biotechnology Letters, 11:709-712, 1989; Macura, et al., Scandinavian Ropy Milk-Identification and Characterization of Endogenous Ropy Lactic Streptococci and their Extracellular Excretion, J. Dairy Sci., 67:735-744, 1984.)
Although EPS-producing organisms in milk have been known for over 150 years (Julie, A. T., Rheological and Microstructural Characteristics of Yogurt Made with Exopolymer-Producing Cultures, Ph.D. Thesis, 1990, University of Minnesota) it is only recently that ropy cultures have been used to produce certain types of yogurt without the addition of stabilizers. Galesloot et al., Manufacture of Stirred Yogurt of High Viscosity, Voedingsmiddelen Technologie, 2:446-448, 1968, describe a process for using a ropy culture in the manufacture of yogurt. The use of ropy cultures of thermophilic lactic bacteria, Streptococcus thermophilus and Lactobacillus bulgaricus, increases the viscosity of yogurt and decreases the susceptibility to synergists. Ropy milk is also produced by some members of the aerogenous group or additional lactic streptococci, such as S. lactis var. taette and S. lactis var. hollandicus. 
Ropy milk of bacterial origin is well known, but is usually considered to be detrimental. The ropiness may be evident only as a slightly abnormal viscosity or it may be so pronounced that the affected milk may be drawn out in long fine threads, and in some instances may assume a gel-like consistency. The ropiness is due to the formation by the bacteria of gums and mucins such as EPS, probably due to the fermentation of the lactose to galactan and dextran. The development of ropiness is closely associated with capsule formation by the bacteria. In many cases, the capsule appears to be degraded as fast as it is formed, as extensive dissolution of outer cell walls occurs and the gummy material is diffused throughout the milk. Such a condition may accompany an unusual proliferation of bacteria or a formation of long-tangled masses of bacterial cells as threads or chains.
There remains a need in the dairy industry to provide a non-fat cream cheese type product, having the appearance, taste, consistency and texture of fat-containing cream cheese. There is further a need to provide improved methods for making an imitation cream cheese product having substantially no fat, and to provide methods for making the imitation cream cheese product that are adapted to economical, large scale commercial operations. There is also a need to provide a non-fat cream cheese like product that avoids the use of a cottage cheese product. The present invention provides a non-fat cream cheese like product that meets these needs.
The present invention provides a process for making a fat-free cream cheese-like product. In the process, a skim milk composition having a high solids content is combined with a source of fat such as cream to form a mixture in which the fat content is less than about 1.5 percent. This mixture is cultured with a ropy culture until the pH reaches a value of about 5.2 to about 4.9. The cultured mixture is blended with a bulking agent (e.g., corn syrup solids) and/or an emulsifier (e.g., sodium tripolyphosphate) to form a blend, which is heated to a temperature of about 60xc2x0 C. to about 65xc2x0 C. A composition including a vegetable gum is then added, and the heating is continued until a temperature of about 80xc2x0 C. to about 90xc2x0 C. is reached. The heated mixture is blended and homogenized to form the fat-free cream cheese-like product, which does not include a cottage cheese composition, and which has the firmness, consistency and flavor of a cream cheese.
Examples of ropy cultures which produce exopolysaccharides in situ include, for example, microorganisms such as Lactococcus lactis ssp. lactis, Lactococcus cremoris, Lactococcus lactis ssp. lactis var. diacetylactis, Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus lactis, Lactobacillus helveticus, Lactobacillus casei and subspecies, Lactobacillus acidophilus, Leuconostoc species, other lactic acid bacteria, and mixtures thereof as well as cultures producing exopolysaccharides.
Examples of bulking agents useful in the present invention include corn syrup, corn syrup solids, modified starch, pectins, microreticulated cellulose, tapioca, waxy maize, potato starch, and mixtures thereof. The bulking agent is generally used to tie up moisture. Furthermore, the emulsifier may be chosen from among sodium tripolyphosphate, disodium phosphate, sodium acid pyrophosphate, sodium citrate, sodium metaphosphate, ammonium phosphate, ammonium citrate, and mixtures thereof. Additionally, the vegetable gum may be a carrageenan, xanthan, locust bean gum, guar gum, cellulose, methycellulose, and mixtures thereof. In a preferred embodiment, manganese or manganese in combination with citrates may be added. Suitable forms of manganese include, for example, manganese carbonate, manganese acetate, manganese sulfate, manganese chloride, as well as mixtures thereof. Citrate can be added as citric acid, sodium citrate, ammonium citrate, as well as mixtures thereof. Such citrate salts may also act as emulsifiers.
The invention additionally provides the fat-free cream cheese-like product obtained using the process of the invention.